NSE4 High Availability and Diagnostics Practice Question
An administrator is troubleshooting a slow web application. The admin suspects that the FortiGate's session table might be full, causing new sessions to be dropped. Which command should the admin use to check the current session table utilization?
⚠ Common exam trap
NSE4 often tests the difference between commands that list sessions versus those that provide summary statistics, causing candidates to choose 'diagnose sys session list' when a quick utilization check is needed.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
diagnose sys session stat
The command 'diagnose sys session stat' provides a summary of session table statistics, including the current session count, maximum session count, and utilization percentage. This directly answers whether the session table is full. It is the correct command to quickly assess session table utilization without listing every session.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
get system performance status
Why it's wrong here
The 'get system performance status' command provides a high-level health snapshot of CPU, memory, and disk usage, but it does not include any session table metrics. Although a slow web application could stem from session table saturation, this command offers no visibility into session count, capacity, or utilization percentage. It is a general system check, not a session-specific diagnostic, so it cannot confirm or rule out session exhaustion.
- ✗
diagnose sys session list
Why it's wrong here
The 'diagnose sys session list' command dumps raw session table entries showing source/destination IPs, ports, protocols, and timers for each active flow. While this is useful for inspecting individual connections, it does not aggregate utilization statistics such as total session count, maximum session capacity, or the current utilization percentage. Manually parsing potentially thousands of session entries to deduce overall session-table pressure is impractical and inefficient during troubleshooting.
- ✓
diagnose sys session stat
Why this is correct
The 'diagnose sys session stat' command is the correct choice because it directly reports session table statistics, including the current number of sessions, the configured maximum, and the utilization percentage. These metrics allow the administrator to quickly determine whether the FortiGate is approaching its session limit, which can cause new connection failures and slow performance for web applications. This command is purpose-built for assessing session-table pressure and is the most efficient way to diagnose session exhaustion.
- ✗
diagnose sys session filter
Why it's wrong here
The 'diagnose sys session filter' command is used to define a filter (e.g., by source IP, destination port, or protocol) that restricts the output of subsequent 'diagnose sys session list' commands. It does not display any session utilization or performance data on its own; running it merely sets a filtering parameter. Since it only affects how session entries are listed later, it provides no information about session counts, maximum capacity, or utilization percentage.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Fortinet exam blueprint
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